The present invention relates to a vehicle antenna attaching apparatus suitable for attaching a rod-shaped antenna to, particular, an inclined wall of the vehicle body.
FIGS. 4 and 5 are views showing a conventional apparatus for attaching a rod-shaped antenna to a vehicle. As shown in FIG. 4, an antenna holding hole 32 is formed in a wall 31 of the vehicle body. A rod-shaped antenna holding portion 40 is inserted into the antenna holding hole 32 and fastened to the vehicle by a plurality of fasteners. The antenna holding portion 40 has a power supply (not shown) provided in the center portion of a cylinder 41. A joint pin 42 having a male screw formed in its outer periphery projects from an upper end portion of the cylinder 41. A feeder 43 extends from a lower end portion of the cylinder 41. The joint pin 42 is electrically connected to the feeder 43 through the cylinder 41. A flange 44 doubling as a grounding member is mounted on the center portion of the cylinder 41.
A bottomless dishlike washer 46 used in common as a grounding member is located on the flange 44, and a boat-shaped ground base 47 is placed on the washer 46. Protruding from the upper surface of the ground base 47 are two pairs of projections 47a and 47b, which are to be put into contact with the inner surface of the wall 31 of the vehicle body. A saw-tooth irregular portion 47c is formed on the bottom of the ground base 47. Thus, the ground base 47 is stably located on the washer 46, inclined at a predetermined angle.
A pad 48 is made of soft rubber. An elongated hole 50 is formed in a hollow semispherical insulative holding member 49. The antenna holding portion 40 projects outwardly from the antenna holding hole 32 and is inserted into the elongated hole 50, when the projections 47a ard 47b of the ground base 47 are put into contact with the inner surface of the wall 31 of the vehicle body. The elongated hole 50 extends in a direction in which the antenna holding portion 40 is inclined, so that the angle can be changed at which the antenna holding portion 40 is inclined to the wall 31 of the vehicle body.
The wall surface of a cover 51 is spherical. A circular hole 51a for inserting the joint pin 42 is formed in the center portion of the cover 51. The cover 51 is mounted on the surface of the insulative holding member 49 so as to close the elongated hole 50. Accordingly, even when the mounting angle of the antenna holding portion 40 is changed, the cover 51 closes a part of the elongated hole 50 which remains on the peripheral portion of the joint pin 42. As a result, rain or the like is prevented from entering through the remaining part of the elongated hole 50 in the vehicle. A fixing nut 53 is mounted on the male screw of the joint pin 42 projecting outwardly through the hole 51a of the cover 51 and the hole 52a of a mounting washer 52. When the fixing nut 53 is screwed down, the washer 52, cover 51, insulative holding member 49 and pad 48 are pressed against the wall 31 of the vehicle body. The antenna holding portion 40 is thereby projected further outwardly from the wall 31. At the same time, the projections 47a and 47b of the ground base 47 are forced into contact with the inner surface of the wall 31. As a result, the wall 31 is clamped mainly by the ground base 47 and the holding member 49, thereby fixing the antenna holding portion 40 to the wall 31. At this time, the antenna is electrically connected to the wall 31 by the flange 44, washer 46 and ground base 47. The fixing nut 53 sets the proximal end portion of a whip-like rod antenna element (not shown) into engagement with the male screw of the joint pin 42 projecting.
The conventional apparatus described above has the following disadvantages:
First, the cost of the apparatus is high, and the use of the apparatus involves a complicated operation. This is because the apparatus has a large number of structural members.
Second, the prior apparatus may fail to attach the rod antenna element reliably to the vehicle. In other words, when the antenna holding angle of the antenna holding portion 40 is changed, the position at which the upper portion of the dishlike washer 46 is contact with the irregular portion 47c of the ground base 47 varies. As a result, that portion of the joint pin 42 which projects upwards through the pad 48, holding member 49, cover 51 and washer 52 also varies in length L. Thus, the length L may be too great or small.
Third, it is difficult for the conventional apparatus to attach the antenna to an inclined wall of the vehicle body, since the hollow holding member 49 is semispherical. In fact, the conventional apparatus cannot attach the antenna to a wall which is inclined at more than 30.degree. to a horizontal plane.